1. Field of the Invention
The invention relates to a pneumatic spring comprising a hose roll bellows (pneumatic spring bellows) made of elastomer material, which in particular is provided with stiffening supports, whereby the ends of the hose roll bellows are pushed onto a connecting element and are secured there by means of a radially deformable clamping ring, which in particular is made of metal (DE-A-36 43 073).
2. Description of the Related Art Including Information Disclosed Under 37 C.F.R. 1.97 and 1.98.
In laid-open document DE-A-21 17 259, the pneumatic spring bellows is made thicker at the outer ends. Conical connecting elements are expected to make the attachment even more secure under tensile stress. The drawback of said design is the increased expenditure in the manufacture of such pneumatic spring bellows. A further drawback is that due to the conical clamping, the pneumatic spring bellows changes its position under tensile load, which means that the constructional position of the bellows is shifted as well.
Laid-open document DE-B-11 52 316 describes a pneumatic spring bellows with core rings incorporated by vulcanization. The pneumatic spring bellows is mounted here on or in conical cylinders and additionally secured by a supporting ring and a bead. The drawback of this solution lies in the high expenditure for the manufacture and for mounting the bellows with fastening means disposed in a pot.
A particularly critical point in pneumatic springs is the region where the connecting element, the hose roll bellows and the clamping ring are joined, especially under the aspects of
influence of material variations;
influence of the manufactured diameter of the pneumatic spring bellows in relation to the clamp-on diameter of the connecting component;
application of the pneumatic spring at different temperatures in association with different types of material employed for the connecting component, the hose roll bellows and the clamping ring; as well as
total thickness of the hose roll bellows in relation to the stiffening support, whereby the share of the elastomer is reduced or reduced even further due to inherent friction.
Now, within the framework of a further development the problem is to improve the tightness of the hose roll bellows in the region of the clamping ring.
Said problem is solved in that the connecting component and/or the clamping ring are made thicker within the clamping region with an elastomer strip, whereby the elastomer strip is a separate structural element with respect to the hose roll bellows. The term xe2x80x9cseparate structural elementxe2x80x9d means in this connection that conditioned by the manufacture, the elastomer strip is a structural element separated from the pneumatic spring bellows, namely as opposed to the embodiments according to DE-A-21 17 259 and DE-B-11 52 316.
The following variations are usefully employed in this connection:
(A) The clamping ring has an elastomer strip applied to it by vulcanizing or gluing, said strip facing the hose roll bellows.
(B) An elastomer strip is present between the hose roll bellows and the connecting element, said elastomer strip being installed in a groove of the connecting element, whereby the elastomer strip may be joined with the connecting element by gluing.
(C) The clamping ring has an elastomer strip, which is gripping around the clamping ring by means of a collar and which faces the hose roll bellows. In addition, the elastomer strip may be glued to the clamping ring.
(D) The elastomer strip is designed in the form of a U-section and encloses the end of the hose roll bellows, which comprises a thickening on both sides.
Irrespective of which of said variations is involved it is advantageous if the thickness of the elastomer strip amounts to 30% to 150%, particularly to 40% to 90% of the normal thickness of the bellows, namely based on the unstressed condition.